Leave a comment on the GearInsight addon page. Comments are checked daily and most data fixes ship within a few days.
curseforge.com/wow/addons/gearinsight
You can also reach us through the addon listing on Wago.io.
addons.wago.io/addons/gearinsight
Please include the class and spec, the item or page concerned, and your region — it makes fixes much faster.